Two known types of communication networks are private networks and public networks. Examples of private networks include communication networks owned or rented by road administration authorities, police, electricity companies, railway companies, and other institutions. These networks are dedicated to communications for the institutions that own or rent them such that third parties cannot access them even if they are idle. Exemplary public networks include public telephone, cellular phone, and the Internet.
While private networks generally provide reliable communications, they have certain concomitant disadvantages. One significant drawback to private networks, such as emergency networks, is cost since they are normally idle. Thus, the overall cost of the network is borne by relatively few users. In addition, many private networks are not as sustainable as desired. The communication networks for road authorities, police and electricity companies, for example, are desired to work under unusual conditions, such as severe storms and earthquakes. However, private networks typically have fewer nodes, and therefore, fewer potential pathways from source to destination. A connection failure between nodes within the private network may significantly impact or prevent communication between first and second locations. In contrast, a public network typically has a relatively large number of potential pathways such that a break between nodes can easily be avoided with relatively little service degradation.
Most private network users, however, cannot replace their private networks with public networks for several reasons. One significant reason is priority control. In one example, a road authority installs a surveillance camera for monitoring traffic conditions and connects the camera to a traffic control center through the road authority private network. If this private network is replaced with a public cellular phone network, there is no impact under normal conditions. However, if a serious traffic accident occurs and a traffic jam is created, many people near the scene will try to use their cellular phones. Since the network users are provided service on a “first come, first serve” basis, the high cellular phone traffic may prevent the surveillance camera from sending its data to the traffic center because the public cellular phone network is busy. In other words, the traffic surveillance system cannot work when it is most needed if it utilizes the public networks instead of the private network.
The IPv6 protocol is an example of a protocol with conventional priority control that classifies messages into eight priority classes depending on the category of each message. Exemplary message categories include background messages (including netnews), email, file transfer, interactive transfer (including telnet), and network control messages. Messages in the same category do not have different priorities. For example, if ten traffic monitoring cameras request to send their images to a traffic control center and if there is a transmission capacity for only one camera, priority control in the IPv6 protocol does not differentiate between the cameras because all of the ten requests are in the same category and the requests are serviced on a “first come, first serve” basis. If one camera keeps occupying the transmission line by continually sending real-time video information, the other nine cameras must wait until the transmission line becomes available in a the carrier sense multiple access/collision detection scheme, for example.
It would, therefore, be desirable to provide an integrated network including a first network, e.g., a private network, and a second network, e.g., a public network, that can utilize the capacity of the first network while giving priority to messages associated with the first network over messages associated with the second network. It would further be desirable to migrate data requests from a first node to a second node based upon the capacity, for example, of the first node.